The present invention generally relates to tubular conduit of the type that might be employed for the housing of underground cables, aerial cables, intrabuilding cables, such as fiber optic cable, coaxial cable, or the like. More particularly, the present invention relates to a fire resistant partitioning device, which may be inserted into such a conduit such that the conduit is divided into separate areas. Specifically, the present invention is directed toward an elongated partitioning device which is fire resistant and flexible, such that it may be inserted into a conduit which is already in place, which may already have at least one cable positioned therein, and which may have turns, bends, or the like therein.
Cable, such as fiber optic communication cable, is often provided underground in great lengths, and may even extend for many miles. It is known in the art to bury the cable in the ground so that the area above ground is not cluttered with the cable and its respective support apparatus. Furthermore, by positioning the cable underground, it is more protected from the weather and other potentially damaging circumstances.
It is also known in the cable art to position the cable within a conduit in order to more fully protect the cable in the ground. The conduit is often formed from lengths of polyvinyl chloride tubing or the like, which is laid in the ground. A rope is then blown through the conduit, and the rope in turn is attached to one of the communication cables. By pulling the rope, the cable is drawn through the conduit. Once in place within the conduit, the cable is protected from damage which may be caused by weather, water and the like.
It has been found that certain rodents will sometimes gnaw through an underground conduit. Hence, much underground conduit is employed which has a diameter of two inches or more, which is large enough to impede damage from most rodents. While such conduit provides excellent protection for communication cable, there is also much unused or xe2x80x9cdeadxe2x80x9d space within such a conduit. With the advent of fiber optic cables, which may be only a half-inch or less in diameter, there is even more dead space within an average conduit.
When a conduit is in place, it may be subsequently desired to run a second communications cable at the same location. As such, it would be desirable from a cost and time standpoint to make use of the dead space within an existing conduit, rather than lay a new length of conduit. However, it has been found that it is difficult to merely insert a second cable into a conduit which already contains a first cable. When a rope is blown into a conduit already containing a cable, or a second cable is xe2x80x9csnakedxe2x80x9d through the conduit, they are often impeded by the first cable, making it impossible to insert the second cable.
It has been suggested to provide a divider to be inserted into a conduit in order to separate the conduit into discrete sections, thus making insertion of the second cable easier. A problem has been encountered in that when conduit is placed over long distances, undulations will invariably occur therein. Also, planned curves, such as at underpasses or the like, will often be encountered rendering the placement of known dividers therein difficult, if not impossible.
A need exists therefore for a device to separate or partition a conduit, such as an underground communication cable conduit, into discrete sections. The device must be capable of being inserted into a conduit that is already in place, which may undulate over many miles, and which may have sharp turns therein. A need also exists for a partitioning device which will provide for improved use of the space within a conduit. Further, a need exists for a partitioning device that may be used within buildings, and which would meet necessary building code requirements for fire resistance, while facilitating cable placement and maintaining installation performance.
The present invention comprises a flexible innerduct structure configured to contain a cable within a conduit. The innerduct structure includes a pair of adjacent strip-shaped layers of flexible material that are joined along their longitudinal edges to define a channel through which the cable can extend longitudinally through the innerduct structure between the layers. In accordance with a principal feature of the invention, the adjacent layers have differing widths between their longitudinal edges, whereby the wider layer bulges away from the narrower layer to impart an open configuration to the channel.
Other principal features of the invention relate to the material of which the innerduct structure is formed. Such features include the structure of the material, such as a woven structure, and further include properties such as melting point, tensile strength, elongation, coefficient of friction, crimp resistance, fire resistance and compression recovery.